A huge pile of wood chips on the Diamond Tree Experts site in South Salt Lake caught fire yesterday. It was the second fire there in a month, and city officials say they’re taking steps to prevent another fire from occurring in the future.

Smoke from the burning mulch pile at about 3600 South was thick enough to shut down I-15 temporarily. Firefighters worked through the night to put out the flames. They think it was started by spontaneous combustion in the decomposing mulch, though the exact cause is under investigation.

South Salt Lake Fire Marshal Boyd Johnson says the company has now moved a lot of the mulch to another site.

Johnson told a news conference at the city's fire headquarters, “I lost count of how many very large semi trucks were moving, being loaded up, of course, and removing the chips, spraying water on it and make sure that they’re not spreading fire from point A to point B. The fire is out, as near as I can tell.”

Sharon Opfermann, who owns a dog boarding business next door says she was really worried last night as the flames spread to a building on the site and threatened a neighboring chemical lab.

In an interview with KUER, Opfermann said, “The thought of trying to move 53 dogs through all of the fire trucks and the water spraying and the people was very daunting.”

South Salt Lake City officials say the company had a good record of compliance with local zoning and business regulations, though the height of the pile had exceeded its permit in recent weeks.

Mayor Cherie Wood says the city is revising its ordinances to make sure nothing like this happens again.

“Business areas do change in the city," Wood told reporters. "What worked, you know, 20 years ago when the zoning ordinances were being written doesn’t necessarily work today.”

Mayor Wood says Diamond Tree is planning to relocate at least part of its business. Company officials couldn’t be reached for comment.